Haven't tried BT yet for the same reasons as Julia but I love the PEI/Ultem surface on my Prusa i3 MK2. After a quick pre-print clean using a paper towel and 70% IPA, prints of PLA, ABS, ASA, PETG, TPU and nGen stick well but pop off easily after a little careful prying.
However, after about 300 hours the surface seemed to have lost some of it's adhesion and several parts got knocked off. Adjusting nozzle temp, bed temp and nozzle gap up and down brought no joy so I took a chance and lightly burnished the surface with fine ScotchBrite wetted with IPA. Viola! It works again and seems to be staying good. Nothing ever dripped on it, nor was it touched by anything except fingers ands scrapers so I don't know if this was due to a natural chemical change in the surface or maybe I was too zealous about cleaning. Whatever, I haven't had to "sand" it again so I'm a happy puppy.
I backed the Steelmans LokBuild KS project, which reports that shipping has begun. So with luck, I should have a 203 X 203mm sheet within a month.... or so. They don't say it's PEI/Ultem but it sound like it. I will try it on the Zortrax and report. Thanks again to Julia for the Z-Sense, which will make this easy.